1. Field of the Invention
The present invention relates to an ink container which is removably accommodated in a casing of an ink jet type recording apparatus to supply ink to a recording head and, in more particular, to a flexible ink bag for storing ink therein.
2. Description of the Related Art
An ink jet type recording apparatus performs a printing operation by reciprocating a recording head in the sheet width direction of a recording sheet. To supply ink from an ink supply source to the recording head while reducing the weight of a reciprocatingly moving section, a recording apparatus, which carries out a large amount of print, generally adopts an arrangement in which the ink supply source is disposed in a casing of the apparatus whereas ink is supplied through a tube to the recording head.
The ink jet type recording apparatus is designed to pressurize ink in a pressure generation chamber to thereby generate ink droplets. If the ink contains air bubbles therein, then the pressure generated is reduced due to such air bubbles to lower the ejection performance of the ink droplets. In order to avoid this problem, the ink jet type recording apparatus requires ink which eliminates dissolved air therefrom.
For this reason, an ink bag 60 shown in FIG. 14 is formed in the following manner: That is, a laminated film having a gas barrier property, which is composed of a polyethylene film and aluminum vapor-deposited on the polyethylene film, is folded at its center so that two half sections of the laminated film are superimposed one on the other. The three sides of the thus superimposed laminated film except for one. short side thereof are connected together by thermal fusion or any other suitable processing. The remaining one short side is sealed with an ink supply hole forming member 61 made of a plastic molding be secured thereto. Further, in order to protect the ink bag 60 from damage due to an external force or the like and to form an ink cartridge, the ink bag 60 is stored in a hard case 62 formed of high-molecular material. In FIG. 14, reference numeral 63 designates a plate member to be fixed to one side of the ink bag 60 to deform the ink bag 60 uniformly and enable detection of the ink end, and 64 designates a cover forming a part of the hard case 62.
However, the ink bag for commercial printing purpose must be supplied or distributed to a user without being stored in the hard case because the capacity of the ink bag 60 must be increased as well as the cost thereof must be reduced.
Therefore, the ink bag itself is required to have such strength as to withstand the distribution and a setting operation for setting the ink bag into a recording apparatus, but the increased strength of the ink bag hinders smooth reduction of the capacity of the bag in conjunction with the ink consumption by printing, which, in turn, incurs an obstacle to the supply of ink to the recording head. The ink bag, which is filled with ink, has such a rounded shape that the central portion of the ink bag is larger in thickness than the peripheral portions thereof, and therefore, the accommodation of the relatively rounded ink bag into an easy-to-handle rectangular case arises another problem in that space utility is low due to the presence of a dead space.
Moreover, if the ink storage capacity of the ink bag is increased, then the shaking or rocking motion of the ink during the distribution causes greater shocks to the ink bag, so that the ink bag is easy to break.